Downhole oil recovery system and method of use

ABSTRACT

An improved hydraulic downhole oil recovery system may incorporate an above ground hydraulic pumping unit and a submersible, bidirectional, reciprocating downhole hydraulic slave cylinder-based pumping unit. Water, rather than hydraulic fluid, may be responsible for actuating the reciprocating downhole pump unit. The water may be transferred through the system using seamless, coil tubing.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of PCT/US2005/045305, filedDec. 13, 2005, which is a continuation-in-part of U.S. application Ser.No. 11/010,641, filed Dec. 13, 2004, now U.S. Pat. No. 7,165,952, andthis application is a continuation-in-part of U.S. application Ser. No.10/945,562, filed Sep. 20, 2004, which is a continuation-in-part of U.S.application Ser. No. 10/945,530, filed Sep. 20, 2004, which is acontinuation-in-part of U.S. application Ser. No. 10/884,376, filed Jul.2, 2004, the disclosures of all of which are incorporated herein byreference.

FIELD

The system described herein generally relates to an improved hydraulicdownhole oil recovery system.

BACKGROUND

Conventional oil recovery systems are hampered by limitations on boththe depth and volume of oil that can be recovered. In fact, known oilrecovery systems can generally recover 400 barrels of oil per day, at adepth of 1000 feet, using full-sized standard surface pumps.

Conventional oil recovery systems are relatively short-lived and requirea high level of maintenance. Current systems rely on large, cumbersomeparts that are prone to leaking and causing wear and tear of standardproduction tubing. In the past, fitting system components and powerfluid tubing within coil tubing has proven to be too difficult.

A large portion of the problems associated with known oil recoverysystems come from the secured-production tubing configuration of thosesystems. Specifically, reciprocation of the sucker rod within theproduction tube causes wear and tear of the tubing. As a result, leaksoften originate within the tubing at the secured reciprocation location.This leads to both inefficiency and environmental contamination. Suchproblems are exaggerated in the common case of deviated oil wells.

Common oil recovery systems also present significant problems at thesurface. Surface pumps are loud, cumbersome, visually offensive,dangerous, and environmentally unfriendly. As such, restrictions areplaced on both where and when these systems can be used. Prohibitivezoning restrictions are often based on the way the pumps look, how theysound, and the inconvenience they cause to people in their proximity.Further, it is widely known in the art that conventional surface pumpsare prone to leaking both oil and hazardous fumes. As such,environmental concerns are very high and periodic maintenance isrequired, while the cost of operation increases and efficiencydecreases.

Surface pumps are also dangerous; each year, there are several injuriesand deaths that result from the operation of such pumps. Thesecasualties often involve children who make their way to the pumps, drawnby curiosity, only to get caught in the moving parts.

There is a narrow range of hydraulically operated oil recovery systemsknown in the art. For instance, Schulte (U.S. Pat. No. 5,494,102)discloses a downhole operated pump having a power piston reciprocated byalternating pressurized hydraulic fluid flow controlled at the surfaceby a hydraulic power control system which quickly reverses the flowdirection.

In view of the limitations and hazards associated with traditional oilrecovery systems, and the defects in those systems, a great need existsfor a system that can operate efficiently and safely.

EXAMPLES AND SUMMARY

The present system does away with the limitations of the prior art. Someembodiments of Applicant's system will be able to recover 1500 barrelsper day, using a fraction of the energy consumed by conventionalsystems. Particular embodiments of the present system may be maintainedon solar energy, which is not feasible with known downhole oil recoverysystems. Some embodiments of Applicant's system provide a much smallersurface unit, with fewer moving parts, and incorporate coil tubing. Assuch, the maintenance and the risk of leaks are reduced. As will befurther discussed, various embodiments of Applicant's system eliminatethe common problems of the prior art through the novel use of coilproduction tubing.

Applicant's system provides a refreshing solution to the problemsmentioned above and avoids the worst characteristics associated withknown surface pumps. Various embodiments of the present system use onlya fraction of the energy required for standard surface pumps. As such,the present system is much smaller and quieter, is easily housed andinsulated, and greatly reduces the likelihood of leaks and the need formaintenance. Further, the present system eliminates the dangersassociated with surface pumps as there are no large, cumbersome movingparts.

Applicant's system is distinguished from Schulte specifically in anumber of ways. While Schulte teaches an apparatus having a power pistonabove the production piston, some embodiments of the present systemprovide for a power piston below the production piston. Suchconfiguration provides greater efficiency and allows the present systemto be operated on much less energy.

Schulte teaches a power piston that runs along the well bore itself.However, some embodiments of the present system provide for a powerpiston/production piston configuration whereby each piston is actuatedwithin a removable tube housing located within the well bore. Thisfeature provides for a straightforward maintenance or replacement schemethat is simply not available with devices known in the art.

Applicant's system also provides a scheme whereby either the volume ofthe power piston or the volume of the production piston may be changedwith respect to one another. As such, the power piston/production pistonratio may be manipulated to vary the power fluid/output fluid ratio fordifferent situations. For example, the size of the power piston may beincreased with respect to the production piston. This scheme will allowthe present system to be operated on an extremely small amount of power.In fact, some embodiments are thought to operate within the range ofsolar power sources. This feature is not available with any knownproducts. Alternatively, the size of the production piston could beincreased with respect to the power piston. This scheme will allow thepresent system to achieve rates of oil production not generallypossible. For example, the present system will be able to produceapproximately 1,500 barrels of oil per day while accepted limitationsfall around 400 barrels of oil per day. As mentioned, the components arehoused in a removable tubing; as such, the power piston/productionpiston ratio may be changed in accordance with changing amounts anddepths of available oil.

Applicant's system further provides a tremendous improvement in oilproduction efficiency. Traditional oil well pump devices can only pumpoil to the surface during an upstroke. However, some embodiments of thepresent system, through employment of a double acting pump and a novelcomponent configuration, allow for oil to be continuously pumped to thesurface. That is, oil is sent to the surface during both the upstrokeand the downstroke. Perhaps of even greater importance, this “doubleaction” is achieved with no greater expenditure of power. Whileproduction is double, energy consumption remains constant.

Certain embodiments of the present system incorporate the use of coiltubing throughout the system. Coil tubing is known in the industry andis typically used to clean sand from well bores; however, no knownproducts have been able to incorporate such tubing to transfer powerfluid and provide housing for system components. Some embodiments ofApplicant's system, however, provide for the novel use of such tubing totransfer power fluid and house components. This feature makes suchembodiments of Applicant's system particularly useful in deviated oilwells when compared to presently available products. Through use of coiltubing, water-based fluid rather than hydraulic fluid, and a uniquecombination of system components, various embodiments of Applicant'ssystem eliminate problems associated with known recovery systems andprovide tremendous progress in view of those systems.

Certain embodiments of the present system are further distinguished overthe prior art in general, and the Schulte patent in particular, by theuse of water-based fluid rather than hydraulic fluid to actuate thedownhole reciprocating pump unit. The substitution of water-based fluidfor hydraulic fluid may appear to be a subtle distinction at firstglance. Nevertheless, the use of water-based fluid in the present systemhas virtually eliminated the most common problems associated withpresently proposed but impractical hydraulic recovery systems,including: the compression of production fluid circulated though thesystem, inflexible fluid transfer lines, fluid friction during downholeand return flow cycles, and fluid viscosity.

In view of the foregoing, some embodiments of the present system providean oil recovery system that pumps oil to the surface during both itsupstroke and its downstroke.

Various embodiments of the present system provide an oil recovery systemthat has a favorable oil production to energy consumption ratio.

Various embodiments of the present system provide an oil recovery systemthat eliminates conventional tubing wear and tear.

Various embodiments of the present system provide an oil recovery systemthat eliminates weak tubing link unreliability.

Various embodiments of the present system provide an oil recovery systemthat eliminates surface leaks.

Various embodiments of the present system provide an oil recovery systemthat eliminates pumping unit liability.

Various embodiments of the present system provide an oil recovery systemthat eliminates submersible pump inefficiencies.

Various embodiments of the present system provide an oil recovery systemthat may be exceptionally useful in deviated oil wells.

Various embodiments of the present system provide an oil recovery systemthat produces and maintains relatively high volume lift in relativelylow production wells.

Various embodiments of the present system provide an oil recovery systemthat may be used in environmentally sensitive locations.

Various embodiments of the present system provide an oil recovery systemthat may be safely used in urban environments.

Various embodiments of the present system provide an oil recovery systemthat may be used in corrosive environments.

Various embodiments of the present system provide an oil recovery systemthat may be used in remote locations.

Various embodiments of the present system provide an oil recovery systemthat contains a surface adjustable lift capacity.

Various embodiments of the present system provide an oil recovery systemthat may be used to recover particularly deep oil deposits.

Various embodiments of the present system provide an oil recovery systemthat may be powered by solar energy or other alternative power sources.

Various embodiments of the present system provide an oil recovery systemthat employs the use of coil production tubing.

Various embodiments of the present system provide an oil recovery systemthat maintains its power piston below its production piston.

Various embodiments of the present system provide an oil recovery systemthat employs the use of pressure controlled surface pumps.

Various embodiments of the present system provide an oil recovery systemthat requires an exceptionally low amount of service.

Various embodiments of the present system provide an oil recovery systemthat has an exceptionally long running life.

As will be discussed in the specification to follow, some embodiments ofthe present system involve a pressure-type pump surface unit. Thissurface unit is modified to read and react to pressure measurementsduring pump cycles so that when pressure builds past a certain point atthe completion of a cycle, the unit “switches” to begin the next cycle.As mentioned, the surface unit of the present system is of apressure-type, and therefore is much smaller, quieter, and cleaner thanstandard oil well surface units.

The surface unit of the present system is connected to a downholeapparatus by a pair of hydraulic powerlines. Some embodiments of thedownhole unit of the present system primarily consist of a power piston,a production piston, a connecting rod, and a series of inlets, valves,and reservoirs. Operation of the system is initiated when power fluid isalternatingly pumped through each powerline, thereby actuating adownhole power piston between a top position and a bottom position.Specifically, as fluid is pumped through the upstroke powerline, thefluid volume of the reservoir below the power piston expands, therebyforcing the power piston upward. During the following downstroke, fluidis pumped through the downstroke powerline, and the fluid volume of thereservoir above the power piston expands, thereby forcing the powerpiston downward.

A connecting rod extends from the power piston to the production piston.In holding the power piston and production piston fixed with respect toone another, the connecting rod traverses both a hydraulic power fluidreservoir and an oil reservoir. Importantly, the connecting rod, incombination with the pump barrel, forms a fluid-tight seal between thepower fluid reservoir and the oil reservoir. This feature allows theconnecting rod to actuate between a top position and a down positionwhile keeping the “dirty” oil environment separate from the “clean”power fluid environment.

In some embodiments, the production piston rests along the top surfaceof the connecting rod and is actuated between a bottom position justabove the power fluid reservoir and a top position just below a one-wayvalve. These one-way valves may be standard “check” valves as known inthe art. That is, each valve may consist of a loosely seated bearingthat rests above a grooved slot. Each bearing may become unseated,thereby allowing fluid to flow in a given direction, yet returns to aseated position to prevent backflow of any fluid.

In some embodiments, as the production piston is actuated from a bottomposition to a top position, oil is cycled from a first inlet, positionedbelow the production piston, to a first reservoir, positioned betweenthe power fluid reservoir and the production piston. During this stage,production oil located in a second reservoir, positioned between theproduction piston and a one-way check valve, is forced through the checkvalve and to the rest of the system. Specifically, the production pistonforces oil through the check valve. As the production piston begins tolower, the check valve returns to the seated position, preventing fluidfrom returning. This action also creates the vacuum that is responsiblefor sucking oil through a second oil inlet into a second oil reservoir.This process is repeated through a series of valves until the oil iscycled to the surface.

In some embodiments, as the production piston is actuated from a topposition to a bottom position, oil is cycled from a second inlet,positioned above the production piston at the completion of adownstroke, into a second reservoir, positioned between the productionpiston and a one-way check valve. During this stage, production oillocated in the first reservoir, positioned between the production pistonand the power fluid reservoir, is forced through an adjacent shaftleading from the first reservoir to a location above the secondreservoir and separated from the first reservoir by a check valve. Saidadjacent shaft also contains its own one-way valve so that fluid onlyflows through the shaft during the downstroke, and no backflow ispermitted.

It is important to note that the general operation and effectiveness ofthe present system do not depend on the exact arrangement of thecomponent parts. Specifically, in some embodiments, the power piston maybe placed below or above the production fluid reservoirs. It is easilyseen that production oil may still be pumped on both an upstroke and adownstroke, with only minor changes needed in the arrangement of thesystem. In each arrangement, the efficiency of the present system ispreserved.

As mentioned, some embodiments of Applicant's system circulate awater-based fluid, rather than hydraulic fluid, throughout the system.This substitution promotes both the novel design and great efficiency ofthe present system. More specifically, the use of water-based fluidprovides for a much greater operating efficiency. That is, typicalhydraulic fluid is compressible and therefore requires significantlymore pump strokes to “pressure up” than a column of water-based fluid.As a result, the efficiency of hydraulic fluid decreases over anyappreciable distance as its compression causes wasted pump strokes,which directly translates to lost power. Because some embodiments of thepresent system use incompressible water-based fluid, problems associatedwith fluid compressibility have been eliminated. Specifically, powerloss is avoided as there is no appreciable loss in efficiency due to thecompression of the circulated production fluid.

Other useful embodiments of the present system are thought to utilizeadditives that may increase the viscosity of the water-based hydraulicfluid. Such may involve the use of “oils” to form emulsions. Theseembodiments are thought to be particularly useful in further reducingfluid friction and further improving operating efficiency.

However, the benefits associated with the present system do not end withuse of water-based fluid. Further benefits of the present system may liein the placement and action of the downhole pump. In some embodiments,the downhole pump is placed below the production oil; as such, thesurface unit is in a mechanically superior alignment. That is, thesurface unit is responsible for actuating only the downhole pump, ratherthan cycling the entire production string through the production tube.This feature alone, in conjunction with an efficient surface unit,provides for an extreme decrease in the energy used during production.

Devices of the past have not been successful in using coil tubing, as ithas proven too difficult to incorporate such tubing within theproduction tube itself. However, Applicant has overcome that obstacle.Some embodiments of the present system provide for coil, flexible tubingcontained within the production tube that allows circulation ofwater-based fluid from the surface to the downhole pump unit. Thisfeature alone, and particularly in combination with coil productiontubing, allows some embodiments of the present system to be useful indeviated wells that would otherwise be inaccessible.

BRIEF DESCRIPTION OF THE DRAWINGS

Applicant's system may be further understood from a description of theaccompanying drawings, wherein unless otherwise specified, likereference numerals are intended to depict like components in the variousviews.

FIGS. 1A-1B are cross-sectional views of one embodiment of a downholeunit of a hydraulic downhole oil recovery system.

FIGS. 2A-2B are cross-sectional views of one embodiment of a downholeunit of a hydraulic downhole oil recovery system.

FIG. 3 is a cross-sectional schematic view of one embodiment of adownhole oil recovery system as used in connection with an oil well.

FIG. 4 is a perspective view of one embodiment of a downhole unit of adownhole oil recovery system.

FIGS. 5A-5B are cross-sectional views of the downhole unit of FIG. 4.

DETAILED DESCRIPTION

With reference to FIG. 3, a hydraulic downhole oil recovery system isidentified generally by the reference numeral 10. In some embodiments,system 10 is primarily made of alloy metal and coil tubing.

Referring to FIGS. 1A-1B, FIGS. 2A-2B, FIG. 3, FIG. 4 and FIGS. 5A-5B,system 10 includes surface pump unit 12. Surface pump unit 12 sendspower fluid 14 through upstroke powerline 16 during one cycle and sendspower fluid 14 through downstroke powerline 18 in a following downstrokecycle. Surface pump unit 12 reversibly engages with powerlines 16 and 18so as to form a fluid-tight seal, such seal being formed by standardtube fittings as known in the art. In some embodiments, surface pumpunit 12 is a pressure pump, modified to contain a “switch off pressuresensor” 13 which reads the pressure at surface pump unit 12 on both theupstroke and the downstroke. At the point each stroke is carried out,pressure increases beyond a preset “switch off” point where sensor 13sends a signal to surface pump unit 12 to begin the next stroke.Further, surface pump unit 12 transfers power fluid 14 by alternatingpressure on both powerline 16 and powerline 18, and such pressure changemay be carried out in a number of ways. Finally, in some embodiments,power fluid 14 may be a water-based fluid. As previously discussed inthe specification, the use of water-based fluid in conjunction withsystem 10 provides its user with a number of advantages.

Both upstroke powerline 16 and downstroke powerline 18 may extend fromsurface pump unit 12 to a downhole unit 11 and follow along the lengthof removable production tube 20. Production tube 20, in someembodiments, reversibly slides along outer shaft 21. In someembodiments, upstroke powerline 16 and downstroke powerline 18 arecomprised of coil production tubing. As previously discussed in thespecification, powerlines made of this material allow some embodimentsof the present system to be particularly useful in deviated oil wells.Perhaps more importantly, powerlines made of this material avoid theproblems otherwise associated with the use of particularly long, jointedtubes in a hydraulic powerline context.

Upstroke powerline 16 leads to upstroke reservoir 22 and is connectedthereto by upstroke fitting 24. Downstroke powerline 18 leads todownstroke reservoir 26 and is connected thereto by downstroke fitting28. In some embodiments, both fitting 24 and fitting 28 are standardtube fittings as known in the art.

As surface pump unit 12 sends power fluid 14 through upstroke powerline16, power fluid 14 fills upstroke reservoir 22 such that its fluidvolume increases, thereby actuating power piston 30 in an upwarddirection so that the fluid volume of downstroke reservoir 26 decreases.Likewise, as surface pump unit 12 sends power fluid 14 throughdownstroke powerline 18, power fluid 14 fills downstroke reservoir 26such that its fluid volume increases, thereby actuating power piston 30in a downward direction, so that the fluid volume of upstroke reservoir22 decreases.

Referring to FIGS. 1A-1B, FIGS. 2A-2B, FIG. 4 and FIGS. 5A-5B, powerpiston 30 is actuated between a top position and a bottom position,where power piston 30 reaches a position just above upstroke fitting 24at the completion of the downstroke in the bottom position; and wherepower piston 30 reaches a position just below downstroke fitting 28 atthe completion of the upstroke in the top position. The pressure changein powerlines 16 and 18, and resulting fluid volume change in reservoirs22 and 26, respectively, is the mechanism responsible for actuatingpower piston 30. In some embodiments, power piston 30 is a “spray metal”plunger, or made of some suitable alloy, and is shaped so as to form afluid-tight fit with removable production tube 20.

Connecting rod 32 is attached to power piston 30 and extends therefrom.Connecting rod 32 is of such length that connecting rod 32 extendsbeyond pump barrel seal 38 during both the downstroke and the upstroke.Rod 32 is actuated between a top position and a bottom position (powerpiston first and second position, respectively) where its top portionrests just above pump barrel seal 38 in a bottom position, at thecompletion of a downstroke; and where its bottom portion rests justbelow pump barrel seal 38 in a top position, at the completion of anupstroke.

The combination of rod 32 and pump barrel seal 38 form a fluid-tightseal; as such, downstroke reservoir 26 in the embodiments shown in FIGS.1A-1B and FIGS. 5A-5B, or upstroke reservoir 22 in the embodiment shownin FIGS. 2A-2B, remains completely sealed from first reservoir 40 andsecond reservoir 42 during both the upstroke and downstroke. In someembodiments, connecting rod 32 and pump barrel seal 38 are fitted sothat a 1/1000th inch gap is found on either side of rod 32. This fit isthought to be most beneficial in that it allows rod 32 to freely movebetween its top and bottom position while preventing production oil fromflowing between rod 32 and pump barrel seal 38. Such a fluid tight sealis particularly beneficial in that it separates the clean environment ofpower fluid 14 from the dirty environment of the oil 62 cycled by system10. As previously discussed in the specification, this has not beenpossible with known hydraulically-driven systems. More typical gasketmaterials, with their erosion in such harsh conditions as are typicallyfound “down hole,” are avoided.

In the alternative, a slightly “looser” fitting may be selected, wherebypower fluid 14, by design, is ejected in some measure as a means forinsuring lack of invasion of outside, possibly corrosive, fluids intothe power piston and cylinder assembly. Such an alternative arrangementmay be appropriate in situations where particulates might score thetighter, substantially fluid-tight, metal-to-metal seal. Also, some formof corrosives-resistant “boot” through which connecting rod 32 extends,by which it is “wiped” as it cycles, may be provided to protect seal 38from particulate contamination.

Production piston 46 is connected to and rests just above rod 32 in theembodiments shown in FIGS. 1A-1B and FIGS. 5A-5B, and just below rod 32in the embodiment shown in FIGS. 2A-2B, and is of a generally solidcylindrical form. Production piston 46 is actuated between a topposition and a bottom position where production piston 46 rests justabove pump barrel seal 38 at the completion of a downstroke in a bottomposition; and piston 46 reaches just below one-way valve 52 at thecompletion of an upstroke, in a top position in the embodiments shown inFIGS. 1A-1B and FIGS. 5A-5B. In the embodiment shown in FIGS. 2A-2B,production piston 46 is actuated between a top position and a bottomposition, where production piston 46 rests just below seal 38 at thecompletion of an upstroke and just above valve 45 at the completion of adownstroke. As previously mentioned in the specification, the volume ofboth production piston 46 and power piston 30 may be changed withrespect to one another. This change in ratio between production piston46 and power piston 30 has particular applicability in a low productionenergy context. Immediately above pump barrel seal 38 is first reservoir40, into which extends the production piston end rod of connecting rod32, which is in turn connected to production piston 46 and the cylinderassembly portion of the downhole pumping unit.

Immediately above pump barrel seal 38 in the embodiments shown in FIGS.1A-1B and FIGS. 5A-5B, and immediately above oil inlet 41 in theembodiment shown in FIGS. 2A-2B, is first reservoir 40. Adjacent tofirst reservoir 40 is first inlet 41. In one embodiment, first inlet 41may have a one-way valve 45 that allows oil 62 to flow into firstreservoir 40 during an upstroke, but does not allow backflow. During anupstroke, oil 62 (oil from a standard type as known in the productionzone of the subject well) is drawn into system 10 through first inlet 41where it travels through and fills first reservoir 40. During adownstroke, oil 62 is pushed from first reservoir 40 by productionpiston 46, and flows through adjacent shaft 48, through one-way valve49, and into upper reservoir 53 (upper reservoir 53 is not shown inFIGS. 5A-5B). Importantly, with this configuration, production of oil isprecisely doubled, yet there is no increase in energy consumption inview of some systems that only pump oil during the upstroke.

Second reservoir 42 is positioned between production piston 46 andone-way valve 52. Adjacent to second reservoir 42 is second inlet 43. Insome embodiments, second inlet 43 may have a one-way valve that allowsoil 62 to flow into second reservoir 42 during a downstroke, but doesnot allow backflow. During a downstroke, oil 62 is drawn into system 10through second inlet 43 where it travels through and fills secondreservoir 42. During an upstroke, oil 62 is pushed from second reservoir42 by production piston 46, and flows through valve 52, through adjacentshaft 48 and into upper reservoir 53. This pumping of production oilduring the upstroke compliments pumping of oil to the surface during thedownstroke so that oil travels to the surface in a continuous manner.Again, by virtue of pumping oil 62 to the surface during both theupstroke and downstroke, production of oil 62 is precisely doubled, yetthere is no increase in energy consumption in view of some systems thatonly pump oil during the upstroke.

While some embodiments shown in FIGS. 1A-1B and FIGS. 5A-5B show firstreservoir 40 and second reservoir 42 as being positioned above powerpiston 30, other useful embodiments are envisioned where first reservoir40 and second reservoir 42, and their respective inlets, are positionedbelow power piston 30 such as the embodiment shown in FIGS. 2A-2B. Insuch cases, the general relationship between the components remains thesame, and the effectiveness of system 10 remains the same. In fact,system 10 is still able to pump twice the amount of oil while expendingthe same amount of energy.

In some embodiments, valve 52 is of a standard type as known in the art.That is, a loosely seated bearing 51 rests upon a grooved slot.Referring specifically to the embodiments shown in FIGS. 1A-1B and FIGS.2A-2B, during an upstroke, bearing 51 becomes unseated and allows oil 62to flow from second reservoir 42, through valve 52, and into upperreservoir 53. Oil 62 easily flows into reservoir 53 as bearing 51becomes unseated and oil 62 is pushed into reservoir 53. During adownstroke, bearing 51 remains seated as fluid flows into reservoir 53from adjacent shaft 48. As system 10 completes a pumping cycle, oil 62is continuously pushed through reservoir 53 and adjoining reservoirs,separated by other one-way valves, until oil 62 reaches the surface.

While alternatives may be employed, one-way valves depicted in someembodiments are a standard ball valve type as are known in the art.These essentially consist of a loosely-seated metal ball or bearingresting upon a complimentarily contoured orifice. When the ball is fullyseated, little or no fluid may pass through the orifice. When pressureis exerted from below the ball or bearing, it is unseated, and fluid maypass through the orifice. However, when pressure is exerted from abovethe ball, it is forced even more into a sealed configuration, and littleor no fluid may pass.

Although the foregoing specific details describe certain embodiments ofthis invention, persons reasonably skilled in the art will recognizethat various changes may be made in the details of this inventionwithout departing from the spirit and scope of the invention as definedin the appended claims and considering the doctrine of equivalents.Therefore, it should be understood that this invention is not to belimited to the specific details shown and described herein.

1. An oil recovery system comprising: a generally hollow production tubehaving an interior space; an upstroke reservoir and a downstrokereservoir disposed in said interior space; a downstroke powerline influid communication with said downstroke reservoir; an upstrokepowerline in fluid communication with said upstroke reservoir; a powerpiston disposed in said interior space of said production tube and influid communication with said downstroke reservoir and said upstrokereservoir; a connecting rod disposed in said interior space of saidproduction tube and having a first end attached to said power piston; aproduction piston being attached to a second end of said connecting rod;a seal disposed between said production piston and said power piston; anoil inlet in fluid communication with an oil reservoir; wherein saidseal separates said downstroke reservoir and said upstroke reservoirfrom said oil reservoir disposed in said interior space of saidproduction tube; wherein said power piston is actuatable over a range ofmotion between a first position and a second position by differentialpressure exerted on said power piston by a power fluid; and an oil inletvalve in fluid communication with said oil inlet.
 2. The oil recoverysystem of claim 1 wherein said downstroke powerline and said upstrokepowerline comprise coil tubing.
 3. The oil recovery system of claim 1wherein said production tube comprises coil tubing.
 4. The oil recoverysystem of claim 1 wherein said production piston is disposed at a bottomend of said connecting rod and said power piston is disposed at a topend of said connecting rod.
 5. The oil recovery system of claim 1wherein said production piston is disposed at a top end of saidconnecting rod and said power piston is disposed at a bottom end of saidconnecting rod.
 6. The oil recovery system of claim 1 wherein said powerfluid comprises water-based fluid.
 7. The oil recovery system of claim 1wherein said production tube is removable.
 8. The oil recovery system ofclaim 1 further comprising a surface pump unit having a sensor whereinsaid surface pump unit is connected to said downstroke powerline andsaid upstroke powerline.
 9. The oil recovery system of claim 1 whereinsaid upstroke powerline and said downstroke powerline extend along alength of said production tube.
 10. The oil recovery system of claim 1wherein said power piston and said production piston are shaped andsized such that production fluid is sucked through said oil inlet valveand into a first oil reservoir upon an upstroke of said power piston.11. The oil recovery system of claim 1 further comprising a second oilinlet in fluid communication with a second oil reservoir located in saidinterior space of said production tube.
 12. The oil recovery system ofclaim 1 wherein said downstroke powerline and said upstroke powerlineare disposed outside of said production tube.
 13. The oil recoverysystem of claim 1 wherein said oil inlet is disposed adjacent to saidseal.
 14. The oil recovery system of claim 13 further comprising a valvedisposed adjacent to said oil inlet valve.
 15. An improved hydraulicdownhole oil recovery system, comprising: elongate, substantiallyseamless fluid transfer tubes; a hydraulic surface unit in substantiallysealed fluid communication with a hydraulic surface unit end of saidfluid transfer tubes, said hydraulic surface unit comprising pressurizedfluid transfer means for transferring a pressurized fluid through saidfluid transfer tubes; and a submersible downhole unit, in substantiallysealed fluid communication with said hydraulic surface unit though asubstantially sealed connection with a downhole unit end of said fluidtransfer tubes, said submersible downhole unit comprising: a powerpiston and cylinder assembly, a power piston component of which isactuatable over a range of motion to and between a first power pistonposition and a second power piston position by differential pressureexerted on said power piston by said pressurized fluid, a connecting rodextending between said power piston and a production piston and cylinderassembly, a production piston component of which is actuatable over arange of motion to and between a first production piston position and asecond production piston position, wherein said connecting rod holdssaid power piston and said production piston in a fixed position withrespect to one another, a plurality of valves configured in relation toa production cylinder portion of said production piston and cylinderassembly for sequentially and repetitively, upon actuation of saidproduction piston effecting, in response to said actuation of saidproduction piston: first drawing production fluid into a first portionof said production piston and cylinder assembly and substantiallysimultaneously ejecting production fluid from a second portion of saidproduction piston and cylinder assembly; second drawing productionfluids into said second portion of said production piston and cylinderassembly and substantially, simultaneously ejecting production fluidfrom said first portion of said production piston and cylinder assembly;and third drawing production fluid into said first portion of saidproduction piston and cylinder assembly and substantially simultaneouslyejecting production fluid from said second portion of said productionpiston and cylinder assembly; a first effluent tube and a secondeffluent tube, configured, respectively, for receiving said productionfluid as ejected from said first and second portions of said productionpiston and cylinder assembly and conveying said production fluid to aproduction fluid collection receptacle; and a hydraulic fluid comprisingwater.
 16. The system of claim 15 wherein said pressurized fluidcomprises water, at least one-half by volume.
 17. The system of claim 15wherein said connecting rod extends from said power piston and cylinderassembly to said production piston and cylinder assembly through anorifice, said orifice having a margin which is metallic and is sized andshaped to form a metal-to-metal seal between said connecting rod andsaid margin of said orifice.
 18. A method of using an improved hydraulicdownhole oil recovery system comprising: selecting a hydraulic downholeoil recovery system, comprising: elongate, substantially seamless fluidtransfer tubes; a hydraulic surface unit in substantially sealed fluidcommunication with a hydraulic surface unit end of said fluid transfertubes, said hydraulic surface unit comprising pressurized fluid transfermeans for transferring a pressurized fluid through said fluid transfertubes; and a submersible downhole unit, in substantially sealed fluidcommunication with said hydraulic surface unit though a substantiallysealed connection with a downhole unit end of said fluid transfer tubes,said submersible downhole unit comprising: a power piston and cylinderassembly, a power piston component of which is actuatable over a rangeof motion to and between a first power piston position and a secondpower piston position by differential pressure exerted on either side ofsaid power piston by said pressurized fluid, a connecting rod extendingbetween said power piston and a production piston and cylinder assembly,a production piston component of which is actuatable over a range ofmotion to and between a fist production piston position and a secondproduction piston position, wherein said connecting rod holds said powerpiston and said production piston in a fixed position with respect toone another, a plurality of valves configured in relation to said aproduction cylinder portion of said production piston and cylinderassembly for sequentially and repetitively, upon actuation of saidproduction piston effecting, in response to said actuation of saidproduction piston: first drawing production fluid into a first portionof said production piston and cylinder assembly and substantiallysimultaneously ejecting production fluid from a second portion of saidproduction piston and cylinder assembly; second drawing productionfluids into said second portion of said production piston and cylinderassembly and substantially, simultaneously ejecting production fluidfrom said first portion of said production piston and cylinder assembly;and third drawing production fluid into said first portion of saidproduction piston and cylinder assembly and substantially simultaneouslyejecting production fluid from said second portion of said productionpiston and cylinder assembly; a first effluent tube and a secondeffluent tube, configured, respectively, for receiving said productionfluid as ejected from said first and second portions of said productionpiston and cylinder assemble and conveying said production fluid to aproduction fluid collection receptacle; and a hydraulic fluid comprisingwater; positioning said hydraulic surface unit substantially at groundlevel and near a well bore of an oil well; positioning said submersibledownhole substantially adjacent to a production zone of said oil well;and actuating said hydraulic downhole oil recovery system for producingoil from said oil well.
 19. The method of claim 18 wherein saidpressurized fluid comprises water, at least one-half by volume.
 20. Themethod of claim 18 wherein said connecting rod extends from said powerpiston and cylinder assembly to said production piston and cylinderassembly through an orifice, said orifice having a margin which ismetallic and is sized and shaped to form a metal-to-metal seal betweensaid connecting rod and said margin of said orifice.